The Becquerel rays and the properties of radium / by Hon. R.J. Strutt.

  • Rayleigh Robert John Strutt Lord, 1875-
Date:
1904
Catalogue details

Licence: In copyright

Credit: The Becquerel rays and the properties of radium / by Hon. R.J. Strutt. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    30/242 (page 18)
    celebrated discoverer of electro-magnetic waves. He found that if a film of gold leaf was placed in the path of the cathode rays, they were able, notwith- standing, to produce some phosphorescence on the glass wall of the tube, though the intensity of the phosphorescence was greatly reduced by passage of the rays through the leaf. Lenard went a step further. He arranged a small window of thin aluminium foil at the end of a vacuum tube. This window was only about inch in diameter ; the object of making it so small was to support the thin leaf as far as possible against the atmospheric pressure, which tends to burst it inwards. With this arrangement (fig. 7) Lenard was able to get the cathode rays through the window and out into the open air. This experiment does not succeed unless the vacuum tube is very highly exhausted, so as to obtain rays of great velocity. The rays of small velocity, obtained at higher pressures, are unable to penetrate the window. Lenard’s experiments, at the time when they were first published, were considered by many to constitute a fatal objection to the corpuscular theory of the rays. It was argued that corpuscles could not penetrate a solid metal window, however thin. This is no longer felt to be a serious